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Abstract

Background

The consumption of foods, especially by children, may be determined by the types of
foods that are available in the home. Because most studies use a single point of data
collection to determine the types of foods in the home, which can miss the change
in availability when resources are not available, the primary objective of this study
was to determine the extent to which the weekly availability of household food items
changed over one month by 1) developing the methodology for the direct observation
of the presence and amount of food items in the home; 2) conducting five in-home household
food inventories over a thirty-day period in a small convenience sample; and 3) determining
the frequency that food items were present in the participating households.

Methods

After the development and pre-testing of the 251-item home observation guide that
used direct observation to determine the presence and amount of food items in the
home (refrigerator, freezer, pantry, elsewhere), two trained researchers recruited
a convenience sample of 9 households (44.4% minority); administered a baseline questionnaire
(personal info, shopping habits, food resources, and food security); and conducted
5 in-home assessments (7-day interval) over a 30-day period. Each in-home assessment
included food-related activities since the last assessment, and an observational survey
of types and amounts of foods present.

Conclusions

The feasibility of conducting multiple in-home assessments was confirmed with 100%
retention of participants through 5 in-home assessments, which paid particular attention
to the intra-monthly changes in household availability in type and amount of foods.
This study contributes to research on home food availability by identifying the importance
of multiple measures, presence of certain foods in the home, and the feasibility of
comprehensive in-home assessments.

Background

Obesity and overweight continue to present broad-scale problems throughout the world,
with high obesity rates in the United States among African American and Hispanic populations
[1-6], persons with low income and educational attainment [7], and individuals living in rural areas [8,9]. There is very little argument that food choice, which is influenced by food available
in the home, affects nutritional health [10]. In fact, Rasmussen and colleagues report home food availability as one of the most
important determinants of eating behavior [11]. Further, household food supplies are considered an intermediate step between community
or neighborhood retail food sources and individual intake [12].

The home food environment supplies more than 70% of the food, by weight, eaten by
Americans, and has been strongly associated with 75% of energy intake and overall
food consumption [10,13-19]. Understanding and changing the home food environment to decrease the consumption
of unhealthy foods requires an accurate measurement of the foods that are available
in the home. Assessing the presence of various foods in the home, including both healthful
and less healthful, may provide understanding of what foods are available for home
consumption and insight needed in order to assess dietary behavior [20-23]. Studies have shown that foods found in pantries are indicators of actual food consumption,
and there has been debate that availability influences food intake [24-26].

A variety of methods for assessing home food supplies have been developed and used
in recent years. Two general approaches have been used to document the presence of
food items in the home; namely, grocery store receipts and household food inventories
[1,2,12,14,15,17,22-25,27-39]. They are similar in that they attempt to measure the presence of certain food items
in the home; however, frequency of observations, the types of food being measured,
and method of the data collection vary [12].

Inventories of household food supplies (HFI), which assess the presence of a wide
range of food items in the home, may be an appropriate method for documenting the
home food environment [34]. Open inventories and predefined inventories are two of the more common household
food inventory methods [40]. Open inventories are customarily conducted by trained researchers who travel to
a subject's home and record all foods present in the home [23,36,41]. In many cases, household inventories have focused on a particular food category
such as fruit and vegetables, fats, soft drinks, or cancer preventing foods, using
a predefined checklist to document whether a food was present in the home [1,14,15,21,24,34,35,38,39]. The method of data collection varies from direct observation in the home by trained
researchers (considered the "gold standard") to telephone-administered or mailed self-report
by participants [12]. Cullen and colleagues concluded that self-reported data are subject to possible
attention, comprehension, memory, and recording errors [21]. Self-reported error is especially of concern in studies conducted outside of the
home, where participants are asked to recall the types of food items present in their
homes when they are in a location other than their homes [14,24,25,28,42].

The number of times an inventory should be conducted in order to describe usual availability
has yet to be determined. Still, most studies choose a single point of data collection
in conducting an inventory of household food supplies [1,12,15,17,21,23-25,28,35,41,42]. Unfortunately, a single point of data collection may miss the influence of intra-monthly
variability on food supplies due to income cycles, purchasing behavior, limitations
in storage and refrigeration, family events, and other factors. Therefore, one measurement
may not accurately represent the foods usually available in the home. Similar to a
single dietary recall, which would not capture variations in dietary habits, a single
food inventory does not capture variation in home food availability [43]. To date, there are a limited number of household food inventory studies that visit
the home on more than one occasion [30,44-47]. Baranowski and colleagues measured the availability of fruits, juice, and vegetables
on three different occasions over the course of one year [47]. Kendall and colleagues collected household food inventory data two times with a
three-week interval between visits [46]. Similarly, Weinstein and colleagues collected food inventory data with the UPC scanner
three times over four weeks (no more than one time per week) [30]. It is not known how many times or the frequency multiple observations should be
conducted in order to obtain a more accurate representation of what is usually in
the home.

Since little is known how household food supplies vary over a month [12], this pilot study expands our understanding household food availability by: 1) developing
the methodology for the direct observation of the presence and amount of food items
in the home; 2) conducting five in-home household food inventories over a thirty-day
period in a small convenience sample; and 3) determining the frequency that food items
were present in the participating households.

Methods

Participants

Eligibility for inclusion in the HFI was limited to women with at least one child
under the age of eighteen living in the same household. Eleven women were recruited
from a local child care center, supermarket, and community action agency through flyers
and word-of-mouth. Two were excluded from the study after multiple failed attempts
to schedule the first home visit, leaving a sample of nine women. The study was completed
in July-August, 2008. Participants received a cash incentive for participation in
the study, which was distributed at the end of the study; $15 for each of the in-home
assessments (HFI and surveys). Informed consent was obtained from all participants,
and the study was approved by the Institutional Review Board at Texas A&M University.

Baseline Questionnaire

During the first home visit, an interviewer-administered questionnaire was completed;
and included the following sections: 1) sociodemographic characteristics, 2) food-related
activities, and 3) food security. Sociodemographic characteristics included participant's age, years of completed education, race/ethnicity, marital
status, number of adults and children residing in the household, ages of children,
household income in 2007, frequency of income payments, automobile ownership, and
nutrition program participation (e.g., Supplemental Nutrition Assistance Program [SNAP],
Women, Infants, and Children Nutrition Program [WIC], School Breakfast Program, and
School Lunch Program). Food-related activities included one-way distance to the store where most of the household's groceries are
purchased; frequency of shopping at this store (weekly, bi-weekly, monthly, or less
than once a month); amount spent on groceries; days since the last food shopping and
amount spent; and frequency of prepared meals purchased from a fast or full-service
restaurant and consumed at home or at the restaurant. Food security was measured using the U.S. Household Food Security Survey Module: Six-Item Short
Form [48]. During the 12 months prior to the first home visit, food security status was operationalized
from the following food security risk situations: purchased food did not last and
money was not available to get more; could not afford to eat balanced meals; adults
in the household cut the size of meals or skipped meals because there wasn't enough
money for food; adults eat less than should eat because there wasn't enough money
for food; and were hungry and did not eat because couldn't afford enough food. The
first three questions also asked the frequency the situation occurred (often, sometimes,
or never). If the participant answered often or sometimes, they were then asked whether
or not this happened every month, 1-2 months, or some months. Scores were calculated
to classify households as food secure (score = 0), marginal food security (score =
1), low food security (score = 2-4), and very low food security (score = 5-6).

Household Food Inventory (HFI)

Household food supplies were inventoried using a HFI instrument that included 251
items and was modified from a 171-item self-reported shelf inventory survey used in
low-income families [29]. The HFI was reviewed by community dietitians in the area; food items were added
to include canned and frozen fruit and vegetables and regional food items. Prepared
foods from full-service or fast food restaurants were not included. In addition, the
instrument was modified to facilitate direct observation of the presence and amount
of specific food items. The HFI consisted of the following categories: fresh, canned,
and frozen vegetables; fresh, canned, and frozen fruit; canned fruit; canned vegetables;
legumes; dairy (milk, yogurt, and cheese); fresh, canned, and frozen meat, poultry,
seafood (fresh or frozen) and other protein foods; cereals, breads, and tortillas;
chips, crackers, and other snacks; frozen desserts (e.g., ice cream and popsicles);
frozen foods (e.g., pizza, tacos or burritos, entrees, breakfast items, and French
fries); beverages; and oils and other fats. Amounts were determined by a count of
the number of items in the case of whole fresh fruit and vegetables, labeling of bottled,
canned, or prepackaged foods, and estimation of previously opened or sliced food items.

Follow-up Questionnaire

A follow-up questionnaire was administered during home visits 2, 3, 4, and 5 to identify
food-related activities that occurred since the prior home visit. The following questions
were included: 1) did you purchase groceries (where, how much was spent, type of purchase,
and method of transportation); 2) did you eat at a fast food restaurant (and frequency);
3) did you eat at a restaurant (and frequency); and 4) did you purchase food prepared
elsewhere to eat at home (and frequency). Frequency responses included once, 2-3 times,
4-5 times, > 5 times, or does not apply.

Data Collection

Data were collected in each participant's home by a trained researcher team during
five home visits, which were scheduled to occur over thirty days; each home visit
was scheduled to occur approximately 6-7 days after the prior home visit. The study
was conducted during July, August, and early September 2008. During the first visit,
the baseline questionnaire was administered, an assessment of kitchen appliances was
completed, and a comprehensive inventory of household food supplies was conducted
in refrigerators, freezers, cabinets, and storage areas and on counter-tops. Participants
were asked to identify all areas that contained any food or beverage items. Photographs
were taken of the appliances and all of the places where food was stored in the home.
During home visits 2-5, a follow-up questionnaire was administered; a complete household
food inventory was assessed; and photographs were taken of food supplies. The researchers
developed a "call out" method where one would call out the presence and amount of
each food item while the other researcher recorded the information. The research team
would randomly re-inventory an area to verify the initial count.

Results

All nine participants completed all aspects of the study; there were no drop-outs
after the first home visit. All of the appointments were conducted with rescheduling
required on two occasions. One participant's child was ill, which required a two-week
interval between her second and third appointments. All other appointments were conducted
with 5-7 days interval between visits; and all 9 women completed all five in-home
assessments. On average the first household food inventories required 45 minutes to
complete; the average time required for the remaining four HFI was 30 minutes.

Characteristics of the participating women and their households are shown in Table
1. Four were non-Hispanic white; one was African American and four were Hispanic. About
two-thirds reported a household income ≤$25,000. Household composition (combined adults
and children) ranged from three (n = 4) to eight; 4 households included 5-8 adults and children. Three households did
not participate in any supplemental nutrition program; six households participated
in at least two nutrition programs (data not shown).

Although one-third (n = 3) were considered food secure, 44.4% (n = 4) were classified as having very low food security. Three households purchased
groceries within seven days of all five assessments and four households for four assessments.
Among these eight participants, six considered no more than one shopping occasion
to be major. Although six participants consumed at least one fast food meal within
seven days of 4-5 of the assessments, only two participants reported purchasing fast
food or other prepared foods for home consumption prior to 4 assessments. Total expenses
for groceries (sum of grocery experiences within seven days of all home assessments)
was <$300 for three households, $300-$420 for five households, and >$450 for one household.

The number of household inventories in which individual fresh fruit and vegetables
and overall variety were present varied (Table 2). Only three households had fresh fruit or vegetables at all five assessments; 44%
of the households had no fruit or vegetables on 1-4 occasions. Weekly presence of
fresh fruit was least consistent among very low food secure households; the presence
of fresh vegetables was inconsistent among very low food secure and food secure households
(data not shown). Apples and bananas were the most frequently observed fresh fruit;
however, the amount of apples present in households with apples ranged from 1-14 apples
(data not shown). In households with bananas, the number ranged from 1-10 bananas.
Household availability of canned fruit and vegetables and legumes (canned and dry)
can be found in Table 3. Seven households had no more than one type of canned fruit (in heavy syrup, light
syrup, or juice) at any assessment; and the amount present varied in three households
(data not shown). Although the most common canned vegetables were tomatoes, green
beans, green peas, carrots, and corn, their presence was not consistent throughout
the month. Further, the amount of canned tomatoes and green beans varied within six
households; and in households with canned corn, the amount remained constant throughout
the month.

Table 3. Percentage of Participants with Can Fruit and Vegetables, Frozen Vegetables and Legumes
Present During Five Household Food Inventories

Household availability of dairy products can be found in Table 4. Two households had whole milk and one had low fat milk on all five occasions (and
the amount varied from week-to-week); 44%-55% had whole or low fat milk present on
1-3 inventory occasions, with different amounts at each inventory (data not shown).
In addition, yogurt and cheese were not consistently available. Table 5 indicates that meats, poultry, and seafood were not consistently available. The availability
of cereals, breads, crackers, prepared desserts, noodles, and rice can be found in
Table 6. White bread and sweetened cereals were found in most homes. In two-thirds of the
homes white bread was present on 4-5 occasions; and in all households sweetened breakfast
cereal was available on 4-5 occasions (with varying amounts from week-to-week). Unsweetened
dry cereal was available in 77.8% of households; however, they were part of the household
food supply on 1-3 occasions in 44.4% of households. Tortillas and biscuits were present
on 1-3 occasions in 4-5 households; prepared desserts (e.g., donuts or regular cookies)
were available during all 5 assessments in one household. With the exception of pasta,
noodles and rice were not usually present. Table 7 shows the frequency of availability of chips, snacks, and frozen desserts; regular
chips were available in all households on at least 4 occasions; the presence of other
snack foods and regular ice cream varied. Table 8 shows the inconsistent availability of beverages.

Table 4. Percentage of Participants with Dairy Present During Five Household Food Inventories

Table 5. Percentage of Participants with Meat/Poultry/Seafood and Other Protein Foods Present
During Five Household Food Inventories

Table 8. Percentage of Participants with Beverages Present During Five Household Food Inventories

Discussion

The availability of foods in the home is one of the factors that may influence the
decisions individuals make with regard to food choice and consumption in the home.
This is particularly important since the type of foods individuals consume affects
their overall health and well being [49]. There are a number of factors that may influence household food availability, such
as household composition, access to food outlets, household income, transportation,
income/resource cycle, and refrigeration/storage facilities. This study examined the
availability of food items in the home, paying particular attention to the changes
in availability that occur throughout the month. This is apparently the first study
to directly observe and document the weekly presence of the type and amount of foods
over the course of one month. This study contributes to research on home food availability
by identifying the importance of multiple measures, presence of certain foods in the
home, and the feasibility of conducting multiple in-home assessments. The results
of this pilot study may be applied to household dietary behaviors in the prevention
and management of obesity, type 2 diabetes, cardiovascular diseases, and hypertension,
and to characterize the overall nutrition climate in households.

Although researchers recognize the importance of documenting the availability of food
items in the home, primarily through a single household food inventory (HFI) [1,12,15,17,21,24,25,28,35,41], little has been reported about the intra-monthly changes in household food supplies,
which may be expected due to income cycles, grocery store trips, competing demands
for resources, and family events. Much like dietary recalls, this variability is ignored
when only one assessment is conducted, which may result in an inaccurate description
of food items available for consumption. The primary objective of this pilot study
was to determine the extent to which the availability of household food items changed
over one month by 1) modifying an existing household food inventory instrument; 2)
determining the feasibility of recruiting and retaining a convenience sample of households
into a study that involved five in-home assessments over one month; and 3) determining
the frequency that food items were present in the participating households.

Using direct observation methodology, which is considered more accurate than self-reported
data [21], this study suggests that a single household assessment may be inadequate in describing
the usual presence of food items in the home. It was evident that several food categories
changed weekly. For example, individual and variety of fresh fruit and vegetables,
milk, canned vegetables, and processed meats (e.g., hot dogs and lunch meat) were
seldom observed during more than three of the five HFI, or the amounts present varied
from week-to-week. Foods like canned fruits were seldom present; and in households
with canned fruit, the amount did not vary from week-to-week. By simply going into
the home on one occasion, we would not have captured "usual" availability. The weekly
variation in all food products suggests the importance of conducting multiple in-home
assessments in order to get an accurate representation of home food availability.
Not only did the amount of food vary from week to week, but the types of foods present
in the home varied as well

For the most part, previous household food inventory studies focused on a limited
number of food categories, used predefined inventories, and did not record the amount
of food present [1,14,15,21,34,35,38,39]. The present study used a comprehensive, predefined inventory that assessed a broad
range of food groups to capture variation in all foods.

One-time HFIs received criticism in the past for only capturing a "cross-sectional
snapshot" of what is usually in the home, and not taking into consideration away-from-home
foods [12]. In response to that criticism, this study administered a short questionnaire at
each in-home assessment to determine the number and type of places where food was
purchased since the previous assessment. This provided insight into away-from-home
food purchases and the weekly amount spent on grocery purchases. The frequency of
grocery store trips varied with each individual. Participants who did not purchase
groceries on a regular basis had less food at certain times of the month. Interestingly,
the four households that did not purchase groceries on a weekly basis all purchased
fast food at least once every two weeks. One particular household did not purchase
groceries every week, but consumed fast food 2-3 times each week. In addition, the
questionnaire addressed underlying issues that may have affected food purchase decisions
such as poverty, number of people living in the home, and availability of food outlets.
All of these factors contribute to the availability of foods in the home, and therefore,
food choice.

While this pilot study determined the feasibility of measuring food inventory at multiple
times, there were several limitations. This study was tedious in households where
the pantry was unorganized. In homes that did not contain a lot of food items, the
inventory was completed in under 30 minutes, but in homes that contained a lot of
food items, the inventory took up to 1 hour to complete each time. A limitation of
the six-item food security module is the lack of identification of food insecurity
among children in the household. In addition, most of the measurements of quantity
were estimates, because the exact measurements of certain food items could not be
obtained. Furthermore, the results may not represent the general population because
of the small sample size (n = 9), which was underpowered for a careful examination
of factors associated with weekly variation. Finally, future work will need to link
household availability, using multiple HFIs, with dietary intake.

Despite the noted limitations to this study, there were a number of strengths. A notable
success was the ability to recruit and retain all participants throughout all parts
of the project. The results of this study emphasize the importance of multiple home
assessments, using direct observation. It is evident that a single point of data collection
does not provide an accurate representation of usual foods present in the home. In
addition, most homes were not visited on the same day of the week, which provided
a better understanding of usual availability. Income cycles were described with the
collection of the demographic information. Since 50% of the participants received
income every 2 weeks, this variation was captured throughout the 30 days of data collection.
The number of home observations that should be conducted over the month has yet to
be determined. It is evident a single measurement does not suffice, but more research
should be done in order to determine the number of times household food inventory
should be conducted, and the frequency.

The availability and accessibility of certain foods within the home has been strongly
associated with food choice [10]. This study examined food availability by conducting multiple in-home assessments
over the course of one month. Weekly availability of household food items was captured
by modifying an existing household food inventory instrument, and recruiting and retaining
a sample of nine households. The findings from this study add to the body of research
on household food availability by providing detailed information on monthly variability.

Competing interests

The authors declare that they have no competing interests.

Authors' contributions

CS and JRS developed the original idea for assessing household food availability.
JRS worked with CS on the development of the instrument and the protocol for collection
of data. CS wrote the first draft of the paper. CS, JRS, AM, and JA read and approved
the final manuscript.

Acknowledgements

This research was supported with funding from the National Institutes of Health (NIH)/National
Center on Minority Health and Health Disparities (# 5P20MD002295) and the Centers
for Disease Control and Prevention (CDC), Prevention Research Centers Program, through
the Center for Community Health Development (#5U48DP000045). The content is solely
the responsibility of the authors and does not necessarily represent the official
views of the NIH and CDC. The authors greatly acknowledge the assistance of Raquel
Flores and the reviewers.